At present the methods for connecting two pipes use screw threads on the end of both pipes. While the threaded ends look like they are fastened tightly, actually there are problems; notably:    1. Conventional connecting the ends of two pipes using internal and external threads. The distal threaded ends of the two pipes are not always aligned. They should be bent slightly for alignment after coupling. This tends to cause damage to the connecting ends and affects the service life of the pipes.    2. To couple the external and internal threaded ends of the pipes, the pipes should be turned to reach the fastening position. Once reached, the two pipes still have to be twisted to attain the most suitable connecting positions. Twisting one of the pipes forcibly could easily generate a gap between the two ends and result in undesirable fluid leakage therein.